// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_COMPILER_DIAMOND_H_
#define V8_COMPILER_DIAMOND_H_

#include "src/compiler/common-operator.h"
#include "src/compiler/graph.h"
#include "src/compiler/node.h"

namespace v8 {
namespace internal {
    namespace compiler {

        // A helper to make it easier to build diamond-shaped control patterns.
        struct Diamond {
            Graph* graph;
            CommonOperatorBuilder* common;
            Node* branch;
            Node* if_true;
            Node* if_false;
            Node* merge;

            Diamond(Graph* g, CommonOperatorBuilder* b, Node* cond,
                BranchHint hint = BranchHint::kNone)
            {
                graph = g;
                common = b;
                branch = graph->NewNode(common->Branch(hint), cond, graph->start());
                if_true = graph->NewNode(common->IfTrue(), branch);
                if_false = graph->NewNode(common->IfFalse(), branch);
                merge = graph->NewNode(common->Merge(2), if_true, if_false);
            }

            // Place {this} after {that} in control flow order.
            void Chain(Diamond& that) { branch->ReplaceInput(1, that.merge); }

            // Place {this} after {that} in control flow order.
            void Chain(Node* that) { branch->ReplaceInput(1, that); }

            // Nest {this} into either the if_true or if_false branch of {that}.
            void Nest(Diamond& that, bool if_true)
            {
                if (if_true) {
                    branch->ReplaceInput(1, that.if_true);
                    that.merge->ReplaceInput(0, merge);
                } else {
                    branch->ReplaceInput(1, that.if_false);
                    that.merge->ReplaceInput(1, merge);
                }
            }

            Node* Phi(MachineRepresentation rep, Node* tv, Node* fv)
            {
                return graph->NewNode(common->Phi(rep, 2), tv, fv, merge);
            }

            Node* EffectPhi(Node* tv, Node* fv)
            {
                return graph->NewNode(common->EffectPhi(2), tv, fv, merge);
            }
        };

    } // namespace compiler
} // namespace internal
} // namespace v8

#endif // V8_COMPILER_DIAMOND_H_
